Two things are mixed here. Injecting a bean into another bean and adding a parameter to commandButton.

Account sender is tried to inject to MoneyTransferBean, however there is no action will be performed since there is no getter setter, so injection will be failed.

sender is tried to set through a commandButton to send as parameter, but there is no implementation for it. @ManagedProperty annotation should be changed for reading the parameter from command button. I assume that sender is set in any place before submitting of commandButton

@ManagedProperty(value="#{param.sender}")
private Account sender;

There are further methods to send or set data in managed beans. Please read the BalusC answer.